#pragma region kyopro_template #include #define pb push_back #define eb emplace_back #define fi first #define se second #define each(x, v) for (auto &x : v) #define all(v) (v).begin(), (v).end() #define sz(v) ((int)(v).size()) #define mem(a, val) memset(a, val, sizeof(a)) #define ini(...) \ int __VA_ARGS__; \ in(__VA_ARGS__) #define inl(...) \ long long __VA_ARGS__; \ in(__VA_ARGS__) #define ins(...) \ string __VA_ARGS__; \ in(__VA_ARGS__) #define inc(...) \ char __VA_ARGS__; \ in(__VA_ARGS__) #define in2(s, t) \ for (int i = 0; i < (int)s.size(); i++) { \ in(s[i], t[i]); \ } #define in3(s, t, u) \ for (int i = 0; i < (int)s.size(); i++) { \ in(s[i], t[i], u[i]); \ } #define in4(s, t, u, v) \ for (int i = 0; i < (int)s.size(); i++) { \ in(s[i], t[i], u[i], v[i]); \ } #define rep(i, N) for (long long i = 0; i < (long long)(N); i++) #define repr(i, N) for (long long i = (long long)(N)-1; i >= 0; i--) #define rep1(i, N) for (long long i = 1; i <= (long long)(N); i++) #define repr1(i, N) for (long long i = (N); (long long)(i) > 0; i--) #define die(...) \ do { \ out(__VA_ARGS__); \ return; \ } while (0) using namespace std; using ll = long long; template using V = vector; using vi = vector; using vl = vector; using vvi = vector>; using vd = V; using vs = V; using vvl = vector>; using P = pair; using vp = vector

; using pii = pair; using vpi = vector>; constexpr int inf = 1001001001; constexpr long long infLL = (1LL << 61) - 1; template inline bool amin(T &x, U y) { return (y < x) ? (x = y, true) : false; } template inline bool amax(T &x, U y) { return (x < y) ? (x = y, true) : false; } template T ceil(T a, U b) { return (a + b - 1) / b; } constexpr long long TEN(int n) { long long ret = 1, x = 10; while (n) { if (n & 1) ret *= x; x *= x; n >>= 1; } return ret; } template ostream &operator<<(ostream &os, const pair &p) { os << p.first << " " << p.second; return os; } template istream &operator>>(istream &is, pair &p) { is >> p.first >> p.second; return is; } template ostream &operator<<(ostream &os, const vector &v) { int s = (int)v.size(); for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i]; return os; } template istream &operator>>(istream &is, vector &v) { for (auto &x : v) is >> x; return is; } void in() {} template void in(T &t, U &... u) { cin >> t; in(u...); } void out() { cout << "\n"; } template void out(const T &t, const U &... u) { cout << t; if (sizeof...(u)) cout << " "; out(u...); } void solve(); #ifdef NyaanDebug #include "NyaanDebug.h" #define trc(...) \ do { \ cerr << #__VA_ARGS__ << " = "; \ dbg_out(__VA_ARGS__); \ } while (0) #define trca(v, N) \ do { \ cerr << #v << " = "; \ array_out(v, N); \ } while (0) #define trcc(v) \ do { \ cerr << #v << " = {"; \ each(x, v) { cerr << " " << x << ","; } \ cerr << "}" << endl; \ } while (0) #else #define trc(...) #define trca(...) #define trcc(...) int main() { solve(); } #endif inline int popcnt(unsigned long long a) { return __builtin_popcountll(a); } inline int lsb(unsigned long long a) { return __builtin_ctzll(a); } inline int msb(unsigned long long a) { return 63 - __builtin_clzll(a); } template inline int getbit(T a, int i) { return (a >> i) & 1; } template inline void setbit(T &a, int i) { a |= (1LL << i); } template inline void delbit(T &a, int i) { a &= ~(1LL << i); } template int lb(const vector &v, const T &a) { return lower_bound(begin(v), end(v), a) - begin(v); } template int ub(const vector &v, const T &a) { return upper_bound(begin(v), end(v), a) - begin(v); } template vector mkrui(const vector &v) { vector ret(v.size() + 1); for (int i = 0; i < int(v.size()); i++) ret[i + 1] = ret[i] + v[i]; return ret; }; template vector mkuni(const vector &v) { vector ret(v); sort(ret.begin(), ret.end()); ret.erase(unique(ret.begin(), ret.end()), ret.end()); return ret; } template vector mkord(int N, F f) { vector ord(N); iota(begin(ord), end(ord), 0); sort(begin(ord), end(ord), f); return ord; } template vector mkiota(int N) { vector ret(N); iota(begin(ret), end(ret), 0); return ret; } template vector mkinv(vector &v) { vector inv(v.size()); for (int i = 0; i < (int)v.size(); i++) inv[v[i]] = i; return inv; } struct IoSetupNya { IoSetupNya() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); cerr << fixed << setprecision(7); } } iosetupnya; #pragma endregion constexpr int MOD = /**/ 998244353; //*/ 1000000007; template struct ModInt { int x; ModInt() : x(0) {} ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} ModInt &operator+=(const ModInt &p) { if ((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if ((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int)(1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; } ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; } ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; } ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; } bool operator==(const ModInt &p) const { return x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const { int a = x, b = mod, u = 1, v = 0, t; while (b > 0) { t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return ModInt(u); } ModInt pow(int64_t n) const { ModInt ret(1), mul(x); while (n > 0) { if (n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { int64_t t; is >> t; a = ModInt(t); return (is); } static int get_mod() { return mod; } }; using modint = ModInt; using mint = modint; using vm = vector; namespace FastFourierTransform { using real = double; struct C { real x, y; C() : x(0), y(0) {} C(real x, real y) : x(x), y(y) {} inline C operator+(const C &c) const { return C(x + c.x, y + c.y); } inline C operator-(const C &c) const { return C(x - c.x, y - c.y); } inline C operator*(const C &c) const { return C(x * c.x - y * c.y, x * c.y + y * c.x); } inline C conj() const { return C(x, -y); } }; const real PI = acosl(-1); int base = 1; vector rts = {{0, 0}, {1, 0}}; vector rev = {0, 1}; void ensure_base(int nbase) { if (nbase <= base) return; rev.resize(1 << nbase); rts.resize(1 << nbase); for (int i = 0; i < (1 << nbase); i++) { rev[i] = (rev[i >> 1] >> 1) + ((i & 1) << (nbase - 1)); } while (base < nbase) { real angle = PI * 2.0 / (1 << (base + 1)); for (int i = 1 << (base - 1); i < (1 << base); i++) { rts[i << 1] = rts[i]; real angle_i = angle * (2 * i + 1 - (1 << base)); rts[(i << 1) + 1] = C(cos(angle_i), sin(angle_i)); } ++base; } } void fft(vector &a, int n) { assert((n & (n - 1)) == 0); int zeros = __builtin_ctz(n); ensure_base(zeros); int shift = base - zeros; for (int i = 0; i < n; i++) { if (i < (rev[i] >> shift)) { swap(a[i], a[rev[i] >> shift]); } } for (int k = 1; k < n; k <<= 1) { for (int i = 0; i < n; i += 2 * k) { for (int j = 0; j < k; j++) { C z = a[i + j + k] * rts[j + k]; a[i + j + k] = a[i + j] - z; a[i + j] = a[i + j] + z; } } } } vector multiply(const vector &a, const vector &b) { int need = (int)a.size() + (int)b.size() - 1; int nbase = 1; while ((1 << nbase) < need) nbase++; ensure_base(nbase); int sz = 1 << nbase; vector fa(sz); for (int i = 0; i < sz; i++) { int x = (i < (int)a.size() ? a[i] : 0); int y = (i < (int)b.size() ? b[i] : 0); fa[i] = C(x, y); } fft(fa, sz); C r(0, -0.25 / (sz >> 1)), s(0, 1), t(0.5, 0); for (int i = 0; i <= (sz >> 1); i++) { int j = (sz - i) & (sz - 1); C z = (fa[j] * fa[j] - (fa[i] * fa[i]).conj()) * r; fa[j] = (fa[i] * fa[i] - (fa[j] * fa[j]).conj()) * r; fa[i] = z; } for (int i = 0; i < (sz >> 1); i++) { C A0 = (fa[i] + fa[i + (sz >> 1)]) * t; C A1 = (fa[i] - fa[i + (sz >> 1)]) * t * rts[(sz >> 1) + i]; fa[i] = A0 + A1 * s; } fft(fa, sz >> 1); vector ret(need); for (int i = 0; i < need; i++) { ret[i] = llround(i & 1 ? fa[i >> 1].y : fa[i >> 1].x); } return ret; } }; // namespace FastFourierTransform template struct ArbitraryModConvolution { using real = FastFourierTransform::real; using C = FastFourierTransform::C; ArbitraryModConvolution() = default; vector multiply(const vector &a, const vector &b, int need = -1) { if (need == -1) need = a.size() + b.size() - 1; int nbase = 0; while ((1 << nbase) < need) nbase++; FastFourierTransform::ensure_base(nbase); int sz = 1 << nbase; vector fa(sz); for (int i = 0; i < (int)a.size(); i++) { fa[i] = C(a[i].x & ((1 << 15) - 1), a[i].x >> 15); } fft(fa, sz); vector fb(sz); if (a == b) { fb = fa; } else { for (int i = 0; i < (int)b.size(); i++) { fb[i] = C(b[i].x & ((1 << 15) - 1), b[i].x >> 15); } fft(fb, sz); } real ratio = 0.25 / sz; C r2(0, -1), r3(ratio, 0), r4(0, -ratio), r5(0, 1); for (int i = 0; i <= (sz >> 1); i++) { int j = (sz - i) & (sz - 1); C a1 = (fa[i] + fa[j].conj()); C a2 = (fa[i] - fa[j].conj()) * r2; C b1 = (fb[i] + fb[j].conj()) * r3; C b2 = (fb[i] - fb[j].conj()) * r4; if (i != j) { C c1 = (fa[j] + fa[i].conj()); C c2 = (fa[j] - fa[i].conj()) * r2; C d1 = (fb[j] + fb[i].conj()) * r3; C d2 = (fb[j] - fb[i].conj()) * r4; fa[i] = c1 * d1 + c2 * d2 * r5; fb[i] = c1 * d2 + c2 * d1; } fa[j] = a1 * b1 + a2 * b2 * r5; fb[j] = a1 * b2 + a2 * b1; } fft(fa, sz); fft(fb, sz); vector ret(need); for (int i = 0; i < need; i++) { int64_t aa = llround(fa[i].x); int64_t bb = llround(fb[i].x); int64_t cc = llround(fa[i].y); aa = T(aa).x, bb = T(bb).x, cc = T(cc).x; ret[i] = aa + (bb << 15) + (cc << 30); } return ret; } }; template struct NumberTheoreticTransform { int base, max_base, root; vector rev, rts; NumberTheoreticTransform() : base(1), rev{0, 1}, rts{0, 1} { assert(mod >= 3 && mod % 2 == 1); auto tmp = mod - 1; max_base = 0; while (tmp % 2 == 0) tmp >>= 1, max_base++; root = 2; while (mod_pow(root, (mod - 1) >> 1) == 1) ++root; assert(mod_pow(root, mod - 1) == 1); root = mod_pow(root, (mod - 1) >> max_base); } inline int mod_pow(int x, int n) { int ret = 1; while (n > 0) { if (n & 1) ret = mul(ret, x); x = mul(x, x); n >>= 1; } return ret; } inline int inverse(int x) { return mod_pow(x, mod - 2); } inline unsigned add(unsigned x, unsigned y) { x += y; if (x >= mod) x -= mod; return x; } inline unsigned mul(unsigned a, unsigned b) { return 1ull * a * b % (unsigned long long)mod; } void ensure_base(int nbase) { if (nbase <= base) return; rev.resize(1 << nbase); rts.resize(1 << nbase); for (int i = 0; i < (1 << nbase); i++) { rev[i] = (rev[i >> 1] >> 1) + ((i & 1) << (nbase - 1)); } assert(nbase <= max_base); while (base < nbase) { int z = mod_pow(root, 1 << (max_base - 1 - base)); for (int i = 1 << (base - 1); i < (1 << base); i++) { rts[i << 1] = rts[i]; rts[(i << 1) + 1] = mul(rts[i], z); } ++base; } } void ntt(vector &a) { const int n = (int)a.size(); assert((n & (n - 1)) == 0); int zeros = __builtin_ctz(n); ensure_base(zeros); int shift = base - zeros; for (int i = 0; i < n; i++) { if (i < (rev[i] >> shift)) { swap(a[i], a[rev[i] >> shift]); } } for (int k = 1; k < n; k <<= 1) { for (int i = 0; i < n; i += 2 * k) { for (int j = 0; j < k; j++) { int z = mul(a[i + j + k], rts[j + k]); a[i + j + k] = add(a[i + j], mod - z); a[i + j] = add(a[i + j], z); } } } } vector multiply(vector a, vector b) { int need = a.size() + b.size() - 1; int nbase = 1; while ((1 << nbase) < need) nbase++; ensure_base(nbase); int sz = 1 << nbase; a.resize(sz, 0); b.resize(sz, 0); ntt(a); ntt(b); int inv_sz = inverse(sz); for (int i = 0; i < sz; i++) { a[i] = mul(a[i], mul(b[i], inv_sz)); } reverse(a.begin() + 1, a.end()); ntt(a); a.resize(need); return a; } vector multiply_for_fps(const vector &a, const vector &b) { vector A(a.size()), B(b.size()); for (int i = 0; i < (int)a.size(); i++) A[i] = a[i].x; for (int i = 0; i < (int)b.size(); i++) B[i] = b[i].x; auto C = multiply(A, B); vector ret(C.size()); for (int i = 0; i < (int)C.size(); i++) ret[i].x = C[i]; return ret; } }; template struct FormalPowerSeries : vector { using vector::vector; using P = FormalPowerSeries; using MULT = function; static MULT &get_mult() { static MULT mult = nullptr; return mult; } static void set_fft(MULT f) { get_mult() = f; } void shrink() { while (this->size() && this->back() == T(0)) this->pop_back(); } P operator+(const P &r) const { return P(*this) += r; } P operator+(const T &v) const { return P(*this) += v; } P operator-(const P &r) const { return P(*this) -= r; } P operator-(const T &v) const { return P(*this) -= v; } P operator*(const P &r) const { return P(*this) *= r; } P operator*(const T &v) const { return P(*this) *= v; } P operator/(const P &r) const { return P(*this) /= r; } P operator%(const P &r) const { return P(*this) %= r; } P &operator+=(const P &r) { if (r.size() > this->size()) this->resize(r.size()); for (int i = 0; i < (int)r.size(); i++) (*this)[i] += r[i]; return *this; } P &operator+=(const T &r) { if (this->empty()) this->resize(1); (*this)[0] += r; return *this; } P &operator-=(const P &r) { if (r.size() > this->size()) this->resize(r.size()); for (int i = 0; i < (int)r.size(); i++) (*this)[i] -= r[i]; shrink(); return *this; } P &operator-=(const T &r) { if (this->empty()) this->resize(1); (*this)[0] -= r; shrink(); return *this; } P &operator*=(const T &v) { const int n = (int)this->size(); for (int k = 0; k < n; k++) (*this)[k] *= v; return *this; } P &operator*=(const P &r) { if (this->empty() || r.empty()) { this->clear(); return *this; } assert(get_mult() != nullptr); return *this = get_mult()(*this, r); } P &operator%=(const P &r) { return *this -= *this / r * r; } P operator-() const { P ret(this->size()); for (int i = 0; i < this->size(); i++) ret[i] = -(*this)[i]; return ret; } P &operator/=(const P &r) { if (this->size() < r.size()) { this->clear(); return *this; } int n = this->size() - r.size() + 1; return *this = (rev().pre(n) * r.rev().inv(n)).pre(n).rev(n); } P pre(int sz) const { return P(begin(*this), begin(*this) + min((int)this->size(), sz)); } P operator>>(int sz) const { if (this->size() <= sz) return {}; P ret(*this); ret.erase(ret.begin(), ret.begin() + sz); return ret; } P operator<<(int sz) const { P ret(*this); ret.insert(ret.begin(), sz, T(0)); return ret; } P rev(int deg = -1) const { P ret(*this); if (deg != -1) ret.resize(deg, T(0)); reverse(begin(ret), end(ret)); return ret; } P diff() const { const int n = (int)this->size(); P ret(max(0, n - 1)); for (int i = 1; i < n; i++) ret[i - 1] = (*this)[i] * T(i); return ret; } P integral() const { const int n = (int)this->size(); P ret(n + 1); ret[0] = T(0); for (int i = 0; i < n; i++) ret[i + 1] = (*this)[i] / T(i + 1); return ret; } // F(0) must not be 0 P inv(int deg = -1) const { assert(((*this)[0]) != T(0)); const int n = (int)this->size(); if (deg == -1) deg = n; P ret({T(1) / (*this)[0]}); for (int i = 1; i < deg; i <<= 1) { ret = (ret + ret - ret * ret * pre(i << 1)).pre(i << 1); } return ret.pre(deg); } // F(0) must be 1 P log(int deg = -1) const { assert((*this)[0] == 1); const int n = (int)this->size(); if (deg == -1) deg = n; return (this->diff() * this->inv(deg)).pre(deg - 1).integral(); } P sqrt(int deg = -1) const { const int n = (int)this->size(); if (deg == -1) deg = n; if ((*this)[0] == T(0)) { for (int i = 1; i < n; i++) { if ((*this)[i] != T(0)) { if (i & 1) return {}; if (deg - i / 2 <= 0) break; auto ret = (*this >> i).sqrt(deg - i / 2) << (i / 2); if (ret.size() < deg) ret.resize(deg, T(0)); return ret; } } return P(deg, 0); } P ret({T(1)}); T inv2 = T(1) / T(2); for (int i = 1; i < deg; i <<= 1) { ret = (ret + pre(i << 1) * ret.inv(i << 1)) * inv2; } return ret.pre(deg); } // F(0) must be 0 P exp(int deg = -1) const { assert((*this)[0] == T(0)); const int n = (int)this->size(); if (deg == -1) deg = n; P ret({T(1)}); for (int i = 1; i < deg; i <<= 1) { ret = (ret * (pre(i << 1) + T(1) - ret.log(i << 1))).pre(i << 1); } return ret.pre(deg); } P pow(int64_t k, int deg = -1) const { const int n = (int)this->size(); if (deg == -1) deg = n; for (int i = 0; i < n; i++) { if ((*this)[i] != T(0)) { T rev = T(1) / (*this)[i]; P C(*this * rev); P D(n - i); for (int j = i; j < n; j++) D[j - i] = C[j]; D = (D.log() * k).exp() * (*this)[i].pow(k); P E(deg); if (i * k > deg) return E; auto S = i * k; for (int j = 0; j + S < deg && j < D.size(); j++) E[j + S] = D[j]; return E; } } return *this; } T eval(T x) const { T r = 0, w = 1; for (auto &v : *this) { r += w * v; w *= x; } return r; } }; using FPS = FormalPowerSeries; // fにa * x^n + bを掛ける void mul_simple(FPS &f, modint a, int n, modint b) { for (int i = (int)f.size() - 1; i >= 0; i--) { f[i] *= b; if (i >= n) f[i] += f[i - n] * a; } } // fからa * x^n + bを割る void div_simple(FPS &f, modint a, int n, modint b) { for (int i = 0; i < (int)f.size(); i++) { f[i] /= b; if (i + n < (int)f.size()) f[n + i] -= f[i] * a; } } // f / gをdeg(f)次まで求める FPS div_(FPS &f, FPS g) { int n = f.size(); return (f * g.inv(n)).pre(n); } modint kitamasa(ll N, FPS &Q, FPS &a) { int k = Q.size() - 1; assert((int)a.size() == k); FPS P = a * Q; P.resize(k); while (N) { auto Q2 = Q; for (int i = 1; i < (int)Q2.size(); i += 2) Q2[i].x = MOD - Q2[i].x; auto S = P * Q2; auto T = Q * Q2; if (N & 1) { for (int i = 1; i < (int)S.size(); i += 2) P[i >> 1].x = S[i].x; for (int i = 0; i < (int)T.size(); i += 2) Q[i >> 1].x = T[i].x; } else { for (int i = 0; i < (int)S.size(); i += 2) P[i >> 1].x = S[i].x; for (int i = 0; i < (int)T.size(); i += 2) Q[i >> 1].x = T[i].x; } N >>= 1; } return P[0]; } struct DynamicUnionFind { unordered_map m; DynamicUnionFind() {} int data(int k) { auto itk = m.find(k); return itk == m.end() ? m[k] = -1 : itk->second; } int find(int k) { int datk = data(k); return datk < 0 ? k : m[k] = find(datk); } int unite(int x, int y) { if ((x = find(x)) == (y = find(y))) return false; auto itx = m.find(x), ity = m.find(y); if (itx->second > ity->second) { ity->second += itx->second; itx->second = y; } else { itx->second += ity->second; ity->second = x; } return true; } int size(int k) { return -data(find(k)); } int same(int x, int y) { return find(x) == find(y); } }; vector fac, finv, inv; void cominit(int MAX) { MAX++; fac.resize(MAX, 0); finv.resize(MAX, 0); inv.resize(MAX, 0); fac[0] = fac[1] = finv[0] = finv[1] = inv[1] = 1; for (int i = 2; i < MAX; i++) { fac[i] = fac[i - 1] * i % MOD; inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD; finv[i] = finv[i - 1] * inv[i] % MOD; } } // nCk combination inline long long COM(int n, int k) { if (n < k || k < 0 || n < 0) return 0; else return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD; } // nPk permutation inline long long PER(int n, int k) { if (n < k || k < 0 || n < 0) return 0; else return (fac[n] * finv[n - k]) % MOD; } // nHk homogeneous polynomial inline long long HGP(int n, int k) { if (n == 0 && k == 0) return 1; // depending on problem? else if (n < 1 || k < 0) return 0; else return fac[n + k - 1] * (finv[k] * finv[n - 1] % MOD) % MOD; } void solve() { NumberTheoreticTransform ntt; auto mul = [&](const FPS::P &a, const FPS::P &b) { auto ret = ntt.multiply_for_fps(a, b); return FPS::P(ret.begin(), ret.end()); }; FPS::set_fft(mul); ini(N, M); vp e(M); in(e); each(p, e) p.first--, p.second--; DynamicUnionFind uf; unordered_map m; cominit(N * 2 + 100); map memo; mint ans = 0; // houzyo rep(b, 1 << M) { uf.m.clear(); m.clear(); vi ps; rep(i, M) { if (!getbit(b, i)) continue; m[e[i].first]++, m[e[i].second]++; uf.unite(e[i].first, e[i].second); ps.pb(e[i].first); ps.pb(e[i].second); } int flg = 0; each(x, m) if (x.second >= 3) flg = 1; if (flg) continue; ps = mkuni(ps); vi used(sz(ps)); // 連結成分ごとにアをする めんどいな int cycle = 0, notcycle = 0, dec = 0; rep(i, sz(ps)) { if (used[i]) continue; // 同じ連結成分は? vi p{ps[i]}; used[i] = 1; for (int j = i + 1; j < sz(ps); j++) if (uf.same(ps[i], ps[j])) p.pb(ps[j]), used[j] = 1; // saikuru? assert(p.size()==uf.size(p.back())); int all2 = 1; each(x, p) if (m[x] != 2) all2 = 0; if (all2) cycle = 1; else notcycle += 1, dec += sz(p); } mint coeff = popcnt(b) % 2 == 0 ? 1 : -1; if (cycle >= 2 or (cycle == 1 and notcycle)) continue; if (cycle == 1) { ans += coeff; continue; } // soreigai // 絶対使う向きつき頂点 notcycle個 // 使わなくてもいい点 N-dec個 trc(cycle, notcycle, dec); // 1ko mukikotei mint cur = 1; if (notcycle >= 2) cur *= mint(2).pow(notcycle - 1) * fac[notcycle - 1]; // soreigai ireru int M = N - dec; // // 1ko // hazimeha notcycle // i ko tukau // no * (no+1) * ... * (no + i - 1) * NCi // koreha? 1st starling? if (memo.find(P{notcycle, dec}) != memo.end()) { cur *= memo[P{notcycle, dec}]; } else { mint x = 0; if (notcycle == 0) { // N choten for (int i = 3; i <= N; i++) { x += mint(COM(N, i)) * mint(fac[i - 1]) / 2; } } else { for (int i = 0; i <= M; i++) { if (dec == 2 and i == 0) continue; else x += mint(COM(M, i)) * fac[notcycle + i - 1] * finv[notcycle - 1]; } } memo[P{notcycle, dec}] = x; cur *= x; } ans += cur * coeff; } out(ans); }